vi over netcat session - shell

Is it possible to use vi over netcat?
server:
mkfifo tun; sh tun | netcat -l 4444 > tun
client:
netcat SERVER_IP 4444
Will gave me remote shell, but it's a problem to send special hot-keys, for example I can't push ESC to enter "normal mode" in vi.
Or best choice will be sed ?

This command runs input from nc as a script, and it will fail for the same reason why this script won't edit a file:
#!/bin/sh
vi file
42G
dd
:wq
You can instead, ironically, use script to avoid running it as a script, and instead get a terminal session to interact with:
server$ mkfifo tun; script -q < tun | netcat -l 4444 > tun
(some netcats require -p before the port above)
Additionally, you should disable local echo and line buffering so that keys pass through the connection immediately rather than when pressing enter:
client$ stty -icanon -echo; nc localhost 4444
You should now be able to edit files in vi.
This is obviously a neat proof of concept only. Non-root users who want to provide robust shell access over the network should use sshd.

Related

User-level command shell change for accessing remote machine with paramiko

I use some code connecting with remote machine with use of paramiko library. The connection is established over tunnelling ssh connection bound to one of the localhost ports. The default shell on the remote machine is tcsh, but my code requires it to run bash. I have tested the sshing some simple commands and it works fine.
$ ssh localhost -p 2222 'echo $0'
tcsh
To change the login shell I have added to my .tcshrc file following two lines:
setenv SHELL /bin/bash
exec /bin/bash --login
The following thing works:
$ ssh localhost -p 2222
[user#remote ~]$ echo $0
/bin/bash
But not the following:
$ ssh localhost -p 2222 'echo $0'
which gives no response. The same for the connections with paramiko established by the code I want to use.
At the moment I am limited only to user-level solutions and would rather not play with the paramiko-using-code itself. Is there anything else I could try here?

Using expect on a Mac to access a router via telnet

I'm trying to write a script on a Mac which should access a router via telnet. This is to enhance the router's power, which cannot be done via web.
The problem is that the telnet channel is blocked, and in order to unlock it I need to run the following instruction:
/users/shared/telnetenable - 200CC8132A36 admin password >/dev/udp/192.168.0.1/23
Now, I can open a telnet connection, but in order to send commands to the router I need to do all that with expect. So, my file begins with:
#!/usr/bin/expect -f
and all instructions are preceded by spawn, e.g.
spawn telnet 192.168.0.1
while the command sent to the router is:
send "wl -a wl0 txpwr 100\n"
My problem is that I do not know how to run via spawn the instruction that unlocks telnet on the router. Can anybody help me?
You don't have to use spawn to run a non-interactive command. Tcl's exec command is enough. For example:
#!/usr/bin/expect
# the ``/dev/udp/host/port'' syntax is bash specific
exec bash -c "/users/shared/telnetenable - 200CC8132A36 \
admin password > /dev/udp/192.168.0.1/23"
spawn telnet 192.168.0.1
... ...
Expect also has a system command so you can also
system "/users/shared/telnetenable - 200CC8132A36 \
admin password > /dev/udp/192.168.0.1/23"

Output from remote server at command prompt

I can connect to remote redis using the telnet command and get the value of "mytest" key. The following is working as expected.
[root#server shantanu]# telnet 10.10.10.100 6379
Trying 10.10.10.100...
Connected to 10.10.10.100 (10.10.10.100).
Escape character is '^]'.
get mytest
$14
this is first
But how do I use it in shell script?
I am used to connect to mysql using the following:
msyql -h10.10.10.100 -uroot -proot#123 -e"show databases"
Is a simialar syntax available for redis?
You can alternatively use redis-cli, included in redis
$ ./src/redis-cli --raw GET key
test
I don't know telnet, but with ssh you can:
ssh user#server "command arg1 arg2 ..."
for example
ssh user#server "ls -ltr | tail"
I would use a tool like wget, which is designed to get content from websites, and is very configurable and automaetable. You might even be able to get away with
export myTestKey=`echo "get mytest" | telnet 10.10.10.100 6379`
If the conversation needs to be more complex than that, I would use telnet in combination with expect, which is designed for trigger and response conversations.

Shell questions

In the following context : VisualVM over ssh
I try to execute the 2 following commands in a single script:
ssh -D 9696 john.doe#121.122.123.124
/usr/bin/jvisualvm -J-Dnetbeans.system_socks_proxy=localhost:9696 \
-J Djava.net.useSystemProxies=true
Having the 2 command like this does not work because the ssh command starts in an interactive mode, so the VisualVM is started after the ssh is closed (explicitly with an 'exit').
What could be a good way to solve that issue?
PS. I am running MacOS X.
try:
ssh john.doe#121.122.123.124 '/usr/bin/jvisualvm -J-Dnetbeans.system_socks_proxy=localhost:9696 -J Djava.net.useSystemProxies=true'
If I understand your use case properly, you want to setup port-forwarding with the ssh connection then the second command is run on the localhost which uses the forwarded port on the localhost. I think you could try the -f or -n options to ssh to achieve this. It does however require a command to be run on the remotehost. You could use a bogus command like echo &> /dev/null for that.
EDIT:
Something like this seemed to work in a naïve test:
ssh -f -D <port> remotehost <dummy_program_that_doesnt_quit>
This is best done using an SSH key and screen, so that we interact with and can close the SSH session.
I'm also presuming jvisualvm takes control of the terminal so that when it exits, we clean up the screen session. If jvisualvm detaches from the terminal, the script immediately jumps to cleaning up the screen session while jvisualvm is running.
ssh-add .ssh/key
screen -dmS sshproxy ssh -i .ssh/key -D 9696 john.doe#121.122.123.124
/usr/bin/jvisualvm -J-Dnetbeans.system_socks_proxy=localhost:9696 \
-J Djava.net.useSystemProxies=true
screen -r -d sshproxy -X quit

How to use SSH to run a local shell script on a remote machine?

I have to run a local shell script (windows/Linux) on a remote machine.
I have SSH configured on both machine A and B. My script is on machine A which will run some of my code on a remote machine, machine B.
The local and remote computers can be either Windows or Unix based system.
Is there a way to run do this using plink/ssh?
If Machine A is a Windows box, you can use Plink (part of PuTTY) with the -m parameter, and it will execute the local script on the remote server.
plink root#MachineB -m local_script.sh
If Machine A is a Unix-based system, you can use:
ssh root#MachineB 'bash -s' < local_script.sh
You shouldn't have to copy the script to the remote server to run it.
This is an old question, and Jason's answer works fine, but I would like to add this:
ssh user#host <<'ENDSSH'
#commands to run on remote host
ENDSSH
This can also be used with su and commands which require user input. (note the ' escaped heredoc)
Since this answer keeps getting bits of traffic, I would add even more info to this wonderful use of heredoc:
You can nest commands with this syntax, and that's the only way nesting seems to work (in a sane way)
ssh user#host <<'ENDSSH'
#commands to run on remote host
ssh user#host2 <<'END2'
# Another bunch of commands on another host
wall <<'ENDWALL'
Error: Out of cheese
ENDWALL
ftp ftp.example.com <<'ENDFTP'
test
test
ls
ENDFTP
END2
ENDSSH
You can actually have a conversation with some services like telnet, ftp, etc. But remember that heredoc just sends the stdin as text, it doesn't wait for response between lines
I just found out that you can indent the insides with tabs if you use <<-END!
ssh user#host <<-'ENDSSH'
#commands to run on remote host
ssh user#host2 <<-'END2'
# Another bunch of commands on another host
wall <<-'ENDWALL'
Error: Out of cheese
ENDWALL
ftp ftp.example.com <<-'ENDFTP'
test
test
ls
ENDFTP
END2
ENDSSH
(I think this should work)
Also see
http://tldp.org/LDP/abs/html/here-docs.html
Also, don't forget to escape variables if you want to pick them up from the destination host.
This has caught me out in the past.
For example:
user#host> ssh user2#host2 "echo \$HOME"
prints out /home/user2
while
user#host> ssh user2#host2 "echo $HOME"
prints out /home/user
Another example:
user#host> ssh user2#host2 "echo hello world | awk '{print \$1}'"
prints out "hello" correctly.
This is an extension to YarekT's answer to combine inline remote commands with passing ENV variables from the local machine to the remote host so you can parameterize your scripts on the remote side:
ssh user#host ARG1=$ARG1 ARG2=$ARG2 'bash -s' <<'ENDSSH'
# commands to run on remote host
echo $ARG1 $ARG2
ENDSSH
I found this exceptionally helpful by keeping it all in one script so it's very readable and maintainable.
Why this works. ssh supports the following syntax:
ssh user#host remote_command
In bash we can specify environment variables to define prior to running a command on a single line like so:
ENV_VAR_1='value1' ENV_VAR_2='value2' bash -c 'echo $ENV_VAR_1 $ENV_VAR_2'
That makes it easy to define variables prior to running a command. In this case echo is our command we're running. Everything before echo defines environment variables.
So we combine those two features and YarekT's answer to get:
ssh user#host ARG1=$ARG1 ARG2=$ARG2 'bash -s' <<'ENDSSH'...
In this case we are setting ARG1 and ARG2 to local values. Sending everything after user#host as the remote_command. When the remote machine executes the command ARG1 and ARG2 are set the local values, thanks to local command line evaluation, which defines environment variables on the remote server, then executes the bash -s command using those variables. Voila.
<hostA_shell_prompt>$ ssh user#hostB "ls -la"
That will prompt you for password, unless you have copied your hostA user's public key to the authorized_keys file on the home of user .ssh's directory. That will allow for passwordless authentication (if accepted as an auth method on the ssh server's configuration)
I've started using Fabric for more sophisticated operations. Fabric requires Python and a couple of other dependencies, but only on the client machine. The server need only be a ssh server. I find this tool to be much more powerful than shell scripts handed off to SSH, and well worth the trouble of getting set up (particularly if you enjoy programming in Python). Fabric handles running scripts on multiple hosts (or hosts of certain roles), helps facilitate idempotent operations (such as adding a line to a config script, but not if it's already there), and allows construction of more complex logic (such as the Python language can provide).
cat ./script.sh | ssh <user>#<host>
chmod +x script.sh
ssh -i key-file root#111.222.3.444 < ./script.sh
Try running ssh user#remote sh ./script.unx.
Assuming you mean you want to do this automatically from a "local" machine, without manually logging into the "remote" machine, you should look into a TCL extension known as Expect, it is designed precisely for this sort of situation. I've also provided a link to a script for logging-in/interacting via SSH.
https://www.nist.gov/services-resources/software/expect
http://bash.cyberciti.biz/security/expect-ssh-login-script/
ssh user#hostname ". ~/.bashrc;/cd path-to-file/;. filename.sh"
highly recommended to source the environment file(.bashrc/.bashprofile/.profile). before running something in remote host because target and source hosts environment variables may be deffer.
I use this one to run a shell script on a remote machine (tested on /bin/bash):
ssh deploy#host . /home/deploy/path/to/script.sh
if you wanna execute command like this
temp=`ls -a`
echo $temp
command in `` will cause errors.
below command will solve this problem
ssh user#host '''
temp=`ls -a`
echo $temp
'''
If the script is short and is meant to be embedded inside your script and you are running under bash shell and also bash shell is available on the remote side, you may use declare to transfer local context to remote. Define variables and functions containing the state that will be transferred to the remote. Define a function that will be executed on the remote side. Then inside a here document read by bash -s you can use declare -p to transfer the variable values and use declare -f to transfer function definitions to the remote.
Because declare takes care of the quoting and will be parsed by the remote bash, the variables are properly quoted and functions are properly transferred. You may just write the script locally, usually I do one long function with the work I need to do on the remote side. The context has to be hand-picked, but the following method is "good enough" for any short scripts and is safe - should properly handle all corner cases.
somevar="spaces or other special characters"
somevar2="!##$%^"
another_func() {
mkdir -p "$1"
}
work() {
another_func "$somevar"
touch "$somevar"/"$somevar2"
}
ssh user#server 'bash -s' <<EOT
$(declare -p somevar somevar2) # transfer variables values
$(declare -f work another_func) # transfer function definitions
work # call the function
EOT
The answer here (https://stackoverflow.com/a/2732991/4752883) works great if
you're trying to run a script on a remote linux machine using plink or ssh.
It will work if the script has multiple lines on linux.
**However, if you are trying to run a batch script located on a local
linux/windows machine and your remote machine is Windows, and it consists
of multiple lines using **
plink root#MachineB -m local_script.bat
wont work.
Only the first line of the script will be executed. This is probably a
limitation of plink.
Solution 1:
To run a multiline batch script (especially if it's relatively simple,
consisting of a few lines):
If your original batch script is as follows
cd C:\Users\ipython_user\Desktop
python filename.py
you can combine the lines together using the "&&" separator as follows in your
local_script.bat file:
https://stackoverflow.com/a/8055390/4752883:
cd C:\Users\ipython_user\Desktop && python filename.py
After this change, you can then run the script as pointed out here by
#JasonR.Coombs: https://stackoverflow.com/a/2732991/4752883 with:
`plink root#MachineB -m local_script.bat`
Solution 2:
If your batch script is relatively complicated, it may be better to use a batch
script which encapsulates the plink command as well as follows as pointed out
here by #Martin https://stackoverflow.com/a/32196999/4752883:
rem Open tunnel in the background
start plink.exe -ssh [username]#[hostname] -L 3307:127.0.0.1:3306 -i "[SSH
key]" -N
rem Wait a second to let Plink establish the tunnel
timeout /t 1
rem Run the task using the tunnel
"C:\Program Files\R\R-3.2.1\bin\x64\R.exe" CMD BATCH qidash.R
rem Kill the tunnel
taskkill /im plink.exe
This bash script does ssh into a target remote machine, and run some command in the remote machine, do not forget to install expect before running it (on mac brew install expect )
#!/usr/bin/expect
set username "enterusenamehere"
set password "enterpasswordhere"
set hosts "enteripaddressofhosthere"
spawn ssh $username#$hosts
expect "$username#$hosts's password:"
send -- "$password\n"
expect "$"
send -- "somecommand on target remote machine here\n"
sleep 5
expect "$"
send -- "exit\n"
You can use runoverssh:
sudo apt install runoverssh
runoverssh -s localscript.sh user host1 host2 host3...
-s runs a local script remotely
Useful flags:
-g use a global password for all hosts (single password prompt)
-n use SSH instead of sshpass, useful for public-key authentication
If it's one script it's fine with the above solution.
I would set up Ansible to do the Job. It works in the same way (Ansible uses ssh to execute the scripts on the remote machine for both Unix or Windows).
It will be more structured and maintainable.
It is unclear if the local script uses locally set variables, functions, or aliases.
If it does this should work:
myscript.sh:
#!/bin/bash
myalias $myvar
myfunction $myvar
It uses $myvar, myfunction, and myalias. Let us assume they is set locally and not on the remote machine.
Make a bash function that contains the script:
eval "myfun() { `cat myscript.sh`; }"
Set variable, function, and alias:
myvar=works
alias myalias='echo This alias'
myfunction() { echo This function "$#"; }
And "export" myfun, myfunction, myvar, and myalias to server using env_parallel from GNU Parallel:
env_parallel -S server -N0 --nonall myfun ::: dummy
Extending answer from #cglotr. In order to write inline command use printf, it useful for simple command and it support multiline using char escaping '\n'
example :
printf "cd /to/path/your/remote/machine/log \n tail -n 100 Server.log" | ssh <user>#<host> 'bash -s'
See don't forget to add bash -s
I created a solution that works better for me by combining the use of a heredoc from Yarek T's answer with the piped cat method from cglotr's answer along with some other tricks for non-interactive login (using sshpass), using variables from the local and remote host in the script, and enabling sudo commands. The code is longer just because it includes some additional tricks that are likely desired, but the original questioner didn't ask for them.
The problem I have with Yarek's answer is that all the warnings and commands in the heredoc print to the screen. The problem I have with cglotr's answer is that is requires a script file and a complex command with additional interaction to execute the script. With my solution, I write a script that does everything by simply calling the script with the remote host IP address as the first argument like this:
./MYSCRIPT REMOTE_IP_ADDRESS
The script to be run on the remote host is saved to a variable within the script on the local host using a heredoc so that you don't need to do any quote escaping. Then, the variable containing the script is echo piped to sshpass. Be sure to indent the commands with tabs and not spaces (you'll get spaces instead of tabs when you copy the code). Here is an example of the remote script within the local script.
!/bin/bash
# Input argument 1 should be the target host IP address (required)
RX_IP="/(\b25[0-5]|\b2[0-4][0-9]|\b[01]?[0-9][0-9]?)(\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}/"
IS_IP=$(echo $1 | sed -nr "${RX_IP}p" | wc -l)
if (( $IS_IP )); then
USERNAME=remoteuser
HOSTNAME=$1
# Export the SSH password to environment variable for sshpass and sudo.
# The space before the command prevents saving the command to history.
export SSHPASS=mypassword;
while read -r -d '' SCRIPT <<-EOS
# Enable sudo commands with the following command.
# The space before echo prevents saving the command to history.
echo $SSHPASS | sudo -Sv
# Do stuff here. Escape variables to be be accessed on the remote host.
# For example, escape print variable in an awk command:
# This command lists all USB block device partitions.
ls -l /dev /dev/mapper | awk '/^b/ && /sd[a-z][1-9]/ {print \$10}'
exit
EOS
echo "$SCRIPT" | sshpass -e ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null ${USERNAME}#${HOSTNAME} &>/dev/null
echo 'DONE'
else
echo "Missing IP address of target host."
echo "Usage: ./SCRIPT_NAME IP_ADDRESS
fi
You need to install sshpass on the local host like this (for Debian based distros).
sudo apt install sshpass
There is another approach ,you can copy your script in your host with scp command then execute it easily .
First, copy the script over to Machine B using scp
[user#machineA]$ scp /path/to/script user#machineB:/home/user/path
Then, just run the script
[user#machineA]$ ssh user#machineB "/home/user/path/script"
This will work if you have given executable permission to the script.

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